Lepton flavor non-universality in the B-sector: a global analyses of various new physics models

Abstract

The measurements of the ratios R_{K^{(*)}} along with R_{D^{(*)}} hint towards lepton flavor non universality which is in disagreement with the standard model. In this work, we reanalyze the four new physics models, which are widely studied in the literature as a candidates for the simultaneous explanations of these measurements. These are, standard model like vector boson (VB), SU(2)_L-singlet vector leptoquark (U_1), SU(2)_L-triplet scalar leptoquark (S_3) and SU(2)_L triplet vector leptoquark (U_3) models. We assume a coupling only to the third generation in the weak basis, so that the b rightarrow s mu ^+ mu ^- transition is generated only via mixing effects. Preforming a global fit to all relevant data, we show that the vector boson model violates the current upper bound on {Br}(tau rightarrow 3mu ) and hence is inconsistent with the present data. Further, we show that within this framework, the U_1 leptoquark model cannot simultaneously accommodate R_{K^{(*)}} and R_{D^{(*)}} measurements. We emphasize that this conclusion is independent of the additional constraints coming from renormaliztion group running effects and high-p_T searches. In addition, we show that the S_3 and U_3 models are highly disfavored by the constraints coming from brightarrow s nu bar{nu } data. Finally, we find a that hypothesis of two LQ particles is also challenged by brightarrow s bar{nu } nu data.